This invention relates to the field of firearms and provisions for modifying semi-automatic firearms for training purposes. In particular, it relates to the assembly of a replacement or xe2x80x9ctrainingxe2x80x9d barrel into firearms that have been modified to fire low-energy ammunition in an unrestrained, blow-back mode.
In military and police firearms applications almost all of the ammunition consumed is used in training. For some training purposes, however, normal ammunition is not appropriate. An alternative type of known training ammunition, represented by U.S. Pat. No. 5,359,937 (adopted herein by reference), fires a low-mass projectile relying on a special, low-energy cartridge designed to provide cycling of suitably modified, recoil-operated automatic and semi-automatic weapons.
An advantage of the low-energy training ammunition is that it has a shorter range and lower penetration capacity than standard ammunition. This permits use of smaller, less secure firing ranges as training facilities. If standard ammunition were accidentally employed in these facilities, unexpected dangers would arise from the increased striking power and range of standard ammunition.
The low-energy cartridge represented by U.S. Pat. No. 5,359,937, in combination with a substitute training barrel, allows normal recoil and cartridge case ejection through a blow-back action. By allowing the firing of appropriate marking cartridges, this system provides for effective close-range, force-on-force training. This system enhances the realism and training value of interactive scenario tactical training because it allows trainees to use their actual service weapons under conditions of greater safety.
When firing standard ammunition with its abundant associated energy many weapons, particularly pistols, lock the barrel to the slide for a portion of the initial recoil. Thus both the barrel and the slide in such weapons move rearwardly together for a period long enough for the projectile to exit the barrel muzzle while the breech is still closed. This allows the chamber pressure to drop before the breach opens to extract and eject the spent cartridge case. Upon unlocking, the slide of these normal weapons continues its rearward travel while the barrel stops in the proper position to receive the next round from the magazine. This next round is then fully chambered by the slide as it returns to its in-battery position.
With a training barrel it is necessary to omit this barrel locking mechanism and, by so doing, the recoil action becomes a pure or direct blow-back of the slide only. This must be done because there is insufficient energy in low-energy training cartridges to precipitate sufficient recoil to unlock the barrel and the slide in their standard configurations.
It may also be necessary to make further modifications to the training barrel, such as by extending the feed ramp, to ensure reliable functioning of the training weapon. As a result, the external geometry of the training barrel may preclude its assembly into the slide and/or receiver without modification to one or both of said slide and said receiver. This is not acceptable because it would render said slide and/or said receiver unusable for subsequent firing of standard service ammunition.
It is, therefore, an objective of this invention to provide a conversion barrel system for this class of training firearm that will allow quick and easy assembly of the training barrel without modification to either the receiver or the slide.
This training barrel allows the weapon to operate with low-energy ammunition. It may also be of a caliber that will exclude operation with standard ammunition. It is a further object to ensure that the weapon can be rapidly reconverted to fire live ammunition again by removing said training barrel and reinstalling said service barrel.
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principal of the invention and the manner of its implementation. The invention in its broadest and more specific forms will be further described, and defined, in each of the individual claims which conclude this specification.
According to the invention an automatic firearm or pistol with a receiver and a slide containing an ejection port that normally operates by barrel recoil and a barrel locking mechanism is modified to operate by direct blow-back operation while maintaining the integrity of the standard slide and standard receiver by insertion of a training barrel. A training barrel of the type addressed by this invention is modified, in part, from the configuration of a standard barrel, by removing the locking mechanism. This allows that the barrel and the slide are no longer held together for the first portion of the recoil cycle. Thus, upon firing a round fitted into the barrel chamber, the slide is free to move rearwards from its in-battery position unencumbered by the barrel. At the same time the training barrel does not move significantly during the firing cycle. By this arrangement maximum energy is transferred to the slide, thereby contributing to reliable weapon cycling.
This conversion is effected by using a training barrel fabricated in two pieces:
(1) a chamber-piece containing a receiver engagement portion that serves as a mounting post and a chamber-piece coupling means at its forward end; and
(2) a muzzle-piece having a complementary coupling means at its chamber end for engagement with the chamber-piece,
wherein the chamber-piece is dimensioned to be installed on the receiver by being passed through the ejection port. For this purpose the length of the chamber-piece may conveniently not exceed the length of the ejection port although this is not essential. Preferably the chamber-piece coupling means is positioned adjacent the chamber, permitting a round when chambered to protrude into the bore of the muzzle-piece. A threaded coupling means is preferred, but other coupling means, such as a bayonet-type may be employed.
The muzzle-piece contains all or the greater part of the barrel bore. Preferably, the chamber portion of the chamber-piece, and the chamber piece itself, are of a length that will permit a round to extend to penetrate into the barrel bore when chambered in the chamber.
The method of the invention comprises the assembly of a standard slide onto a standard receiver without the training barrel being present. The training barrel is provided in two parts: a chamber-piece and a muzzle-piece which may be coupled together. The chamber-piece is lowered from above and fitted onto a seat in the form of a locking block present within the receiver by passing it through the ejection port of the slide. The barrel portion or muzzle-piece of the training barrel is then inserted through the muzzle end of the slide and attached to the chamber-piece as by threading it in place. A mounting post carried by the chamber-piece keys into the locking block and, with the muzzle-piece in place, the entire, composite training barrel is substantially fixed to the receiver (subject only to an insignificant amount of xe2x80x9cplayxe2x80x9d).
The foregoing summarizes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which now follow.